The present invention generally relates to lighting. More specifically, the present invention relates to LED lighting control and monitoring.
Electrical systems that have different power sources can exist at different potentials with reference to each other. Often, the point of lowest potential in the system functions as a ground, such that any point electrically connected to that point will have zero potential with reference to that point. Ohm's law (V=I×R or I=V/R) states that for a given resistance, current flow through a conductor between two points is directly proportional to the potential difference across the two points. With this in mind, a point designated as ground and having zero potential within a given system can still have a non-zero potential with reference to a similar system that has a different power source. Therefore control or monitoring systems that connect the reference (usually negative) leads of different power systems (for example the drivers which supply current to LED fixtures by referencing them to a common reference point or ground on the control board) will likely allow ground-path currents or EMI into the system, which can interfere with system operation, or cause signal degradation or even possible component damage.
One example of this type of situation is a type of LED lighting system used for sports and wide-area lighting. These systems are powered by AC three-phase mains power, and use drivers which provide current-controlled DC power to LED fixtures. For some of these drivers, the DC negative lead (usually the reference lead or ground lead) may not be isolated from the AC power source, which itself can be at a different reference potential relative to other AC power sources; the result is that the ground or reference potential for any given driver DC power output can have a different potential from another driver or reference.
LED lighting systems, particularly as used for sports fields or wide-area lighting, can require multiple drivers at a given pole or mounting location in order to provide power for several LED fixtures. Depending on many factors, the number of drivers needed at a single location can range from only one, where only one or two fixtures are needed, to four, eight, or even more, if many fixtures are needed to provide a high level of illumination. One method of controlling multiple fixtures is simply to have a single control module or analogous device for each driver. This is often not desirable since many controllers would be required whenever multiple drivers are used. Another method, which will be discussed further below, is to construct a control module or device that has a fixed number of channels, for example four. By channels it is meant an independent hardware component that coordinates all I/O to the controller. This hardware can be physically located on the same circuit board in close proximity to other channels and to the controller, but which essentially sends information which relates to a remote device and which has used components unique to the channel to process, modify, or interpret already processed data to the controller. So for a controller with four channels, each channel processes information about the device it controls or monitors, and sends the processed results, not the raw information, back to the main controller. This kind of controller works well for use with, e.g., four drivers and has many benefits. However for the locations needing a number of drivers not divisible by four, it means one or more of the channels will not be used which can be a waste of resources. Further, since the control program or schedule for the fixtures at a single pole or location is often the same, whether there are a few or many fixtures, requiring one controller for every four fixtures is not always ideal. For example, it requires that multiple channels are needed in the lighting control systems just to turn on or off or to dim the fixtures at that one location. For a field or sports complex with many different poles, this can increase the cost and complexity of lighting control systems.
Further, LED lighting covers a wide range of lighting needs, for example lighting sports fields at levels sufficient for television broadcast, lighting pedestrian areas at a much lower level, lighting emergency exits, etc. The controls and drivers needed for different lighting applications can be quite different, since sports field lighting may use high power drivers each providing 1000-1500 watts to an LED fixture, while pedestrian lighting may use 100 watt drivers, and emergency exit lighting might use LED fixtures of 5 watts or less that have integrated drivers; further all of these drivers may have different communications protocols and may be variously isolated, partially isolated, or non-isolated. Still further, it may be desired to add additional LED lighting systems having different control systems to an existing installation, where it would be preferred to use an existing controller rather than adding a new controller. And one driver out of three or four in an existing system could fail and need to be replaced; if the remaining drivers are still workable, it might be desirable to replace the one driver with one of a different control type or isolation topology, while not replacing the remaining drivers. For example, the identical driver might no longer be available, or a newer driver could be available which is more efficient than the older drivers but which does not warrant changing all the drivers. And further still, since new systems and devices which provide benefits to the kinds of venues that use LED lighting are constantly becoming available, the ability to control electronic devices not limited to LED lighting could be highly desirable.
In all of these circumstances, the ability to control drivers having different control or isolation configurations, or to control other electronic devices would be beneficial.
Therefore it is desirable to find a way to isolate the control and measurement functions from the different ground potentials, to allow lighting controllers to address as few or as many drivers as are needed at a single pole or location, and further to provide varied, flexible means, apparatus, system, technique, or method for interfacing with LED drivers and other electronic devices. In the current state of the art, as far as can be determined, there is no method, system, or apparatus that provides these functions. This is a serious deficiency for which a solution will be highly beneficial.
From the foregoing it can be seen that there are competing interests and factors in supplying both control/power functionality and communication functionality within these types of systems. For example, certain power levels in the use of certain types of components and combination of components for certain situations. Yet practicality, economics, and sometimes even conventional-wisdom may work against those components or combination of components. Furthermore, when trying to incorporate a variety of different functional sections and electrical systems, a balancing of factors many times must take place. Some of the factors can be antagonistic to one another. As mentioned above, isolation of functionality may sometimes be indicated but practicality works against that. Sometimes conventional-wisdom would default towards ignoring some potential issues such as being at risk of unwanted current flow between functional sections. Still further, flexibility can be important. But this can be antagonistic to universality. For example, it can be desirable to substitute different types of components into a system. But inherently it is difficult to design the system to accommodate this.
Space and economy also come into play. But sometimes they are antagonistic to the functions of the electrical circuit.
Thus, there is room for improvement in the art.